Matt,
Instances can be grouped, but only on dashboards. It's not possible to be able to hide instances from one group to another, on the devices tab. I get the idea and I'd love to see it, but it's fundamentally difficult do to in the current architecture.
Michael,
I do this all the time with switch interfaces. If the interface has a description, or some value we can use (interface number, etc), we can pull those instances out into a new datasource, using AD filters. ie, you'd have an interfaces datasource looking at end user interfaces (with status alerts turned off so they don't trigger alerts when people take their machines home), and another that looked only at the important interfaces (with critical alerts turned on for status, because these are network infrastructure). The filters regex match/notmatch against the instances- "uplink" for example. Quite simple and really powerful. Have been meaning to write a blog about this, I'll try to finish it up soon.
